过渡金属基蒙脱石吸附含盐水中氨氮机理研究  

Mechanism of Adsorption of Ammonia Nitrogen in Saline by Transition Metal Montmorillonite

作　　者：彭志业 陈云嫩[1] 何彩庆 崔鹤 PENG Zhiye;CHEN Yunnen;HE Caiqing;CUI He(Jiangxi Key Laboratory of Mining&Metallurgy Environmental Pollution Control,Jiangxi University of Science and Technology,Ganzhou 341000,China)

机构地区：[1]江西理工大学江西省矿冶环境污染控制重点实验室,江西赣州341000

出　　处：《有色金属工程》2023年第3期136-145,共10页Nonferrous Metals Engineering

基　　金：国家自然科学基金资助项目(51864021)。

摘　　要：通常离子交换吸附法和生物法对水中氨氮的处理效率较高,但盐分的存在使离子交换吸附法因盐离子的竞争作用而使其处理效率下降,盐分也因抑制了微生物的活性而使生物法处理效率下降。分别采用Co、Ni、Cu和Zn四种过渡金属负载于蒙脱石,得到四种过渡金属基蒙脱石。在含盐且溶液pH值9.0~11.5内,与蒙脱石相比,四种过渡金属基蒙脱石除氨氮性能大大提升。比表面积测试发现,过渡金属基蒙脱石拥有更大的内层空间,其比表面积也大幅提升;且与蒙脱石相比,过渡金属的改性使蒙脱石孔径变小,这是蒙脱石层内离子半径较小的Na+和离子半径较大的过渡金属离子发生交换。不仅能谱分析证实这一结论,即蒙脱石经过过渡金属改性之后,Na元素相对含量由9.46%降至2.75%~5.48%;XRD也证实了这点,即与蒙脱石相比,位于31.8°、45.5°、56.5°和75.3°特征峰的NaCl,四种过渡金属基蒙脱石对应衍射角特征峰强度都减弱甚至消失,说明金属改性过程中蒙脱石发生了同晶置换,层内Na+等物质被Co^(2+)、Ni^(2+)、Cu^(2+)、Zn^(2+)成功交换。SEM图像可见蒙脱石表面结构较为紧密,过渡金属基蒙脱石表面多孔且不平整,出现明显沟壑,这些微观结构使金属基蒙脱石具有更大比表面积、更多吸附位点。四种过渡金属基蒙脱石在不同含盐量影响下对氨氮的吸附性能有类似趋势,即铜基蒙脱石铜基蒙脱石始终保持最佳,这不仅是Cu^(2+)离子与NH3分子之间的配位能力最强,且其内层羟基最高,内层间距最大。光电子能谱分析可知,铜基蒙脱石除氨氮后的N1s,表明铜基蒙脱石与氨氮形成了配位共价键,同时还存在离子交换和静电吸引作用;其吸附过程更符合准二级动力学模型;全谱图发现,除氨氮前后的铜基蒙脱石其N元素从0增至2.78%。In general, ion-exchange adsorption and biological method have higher treatment efficiency for ammonia nitrogen in water, but the existence of salt makes the treatment efficiency of ion-exchange adsorption method decreased due to the competition of salt ions, and the salt also inhibits the activity of microorganisms, which makes the biological method′s treatment efficiency decreased. Four transition metals(Co, Ni, Cu and Zn) were used to support montmorillonite, and four transition metal-based montmorillonite were obtained. Compared with montmorillonite, the ammonia-nitrogen removal performance of the four transition metal-based montmorillonite is greatly improved in the range of saline solution pH 9.0-11.5. The specific surface area test shows that the transition metal montmorillonite has larger inner space, and its specific surface area is also greatly improved. Moreover, compared with montmorillonite, the modification of transition metals makes the pore size of montmorillonite smaller, which is the exchange between Na+with smaller ionic radius and transition metal ions with larger ionic radius in the montmorillonite layer. This conclusion is confirmed by energy spectrum analysis, that is, the relative content of Na decreases from 9.46% to 2.75%-5.48% after the modification of montmorillonite by transition metal. X-ray diffraction analysis also confirmed this point, that is, compared with montmorillonite, NaCl at the characteristic peaks of 31.8°, 45.5°, 56.5° and 75.3°, the intensity of diffraction angles corresponding to the four transition metal-based montmorillonite weakened or even disappeared, indicating that the montmorillonite underwent iso-crystal replacement in the process of metal modification. In the layer, Na+and other substances were successfully exchanged by Co^(2+), Ni^(2+), Cu^(2+), Zn^(2+). Scanning electron microscopy shows that the surface structure of montmorillonite is relatively compact, and the surface of transition metal-montmorillonite is porous and uneven, with obvious gullies.

关 键 词：含盐水 氨氮 过渡金属 配体交换 蒙脱石 

分 类 号：X703[环境科学与工程—环境工程]